1. Field of the Invention
The present invention relates to a method and apparatus for generating energy from the motion of waves in a body of water, such as seas, oceans and lakes.
The purpose of this invention is to enable the harvesting of renewable wave energy from the oceans and lakes of the world.
2. Description of the Prior Art
Many devices have been proposed in the past to accomplish this purpose. Very few have become commercialized because of one or more of the following reasons;
1/The device is too expensive to produce and hence unable to compete with conventional fossil fuel means of energy production.
2/Many of the devices are of high complexity. Components such as springs, running rigging, pulleys, bearings, gearboxes and other rotating equipment, electrical or electronic controls, all have limited service lives, especially in a marine environment.
3/Many of the devices attempt to generate electricity at sea and then to transmit it ashore. Water, especially sea water and electricity, like water and oil, do not mix. Any attempt at doing this will result in high construction costs and long term unreliability due to faults and corrosion problems.
4/Many devices are unable to withstand storms and high waves.
5/Many devices have not taken into account the long term serviceability and maintenance requirements which are necessary to achieve a life expectancy of at least 20 years, which is the industry norm.
6/Many devices require the use of oils, heavy metals and other materials which, if released, can be potentially damaging to the environment.
Accordingly, there is a need for an improved system and method for generating energy from waves in bodies of water that addresses some or all of the above problems.
The prior art describing devices for the capture of sea wave energy is extensive. Prior art which is closely related to the this proposed device is however limited to a few examples. The most relevant are as follows;
WINDLE, EP 0265594 discloses a float operated reciprocating pump which relies upon springs, or weights or floats with or without ropes and pulleys to actuate the return stroke. Windle also discloses the various configurations of mounting a reciprocating pump with respect to the float and foundation. The pump may be inverted, may be mounted within the float or within the sea bed or in other configurations.
JANODY, FR 2800423 also discloses a spring to actuate the return stroke.
BURNS, CA 2619100 discloses a pump utilizing a hollow piston but only proposes using gravity to actuate the return stroke.
ONO, U.S. Pat. No. 4,398,095 discloses a hydraulic method of actuating the return stroke by utilizing the pressure difference between air at the surface and the pressure of the water at depth.
WOOD, GB 2 428 747 discloses a wave energy system with a float moored to a single hydraulic cylinder.
Similarly, HICKS et al., U.S. Pat. No. 4,326,840 discloses a wave driven pump having a float moored to a hydraulic cylinder at the seabed. A wave powered pumping apparatus and method are also disclosed by WINDLE, U.S. Pat. No. 4,883,411.
Wave energy systems are also disclosed by MYUNG, GB 2281943 and SMITH, GB 2445951.